A prior-art side impact protection member of the type described in the introduction (WO 94/07709 A1) comprises a high-strength steel material with a bead, which has a trapezoidal profile. Such a profile is manufactured by expensive hot forming. The side impact protection member is fastened with its flat ends to associated components of the motor vehicle door, e.g., by weld connections or screw connections. At the required flexural strength, it has a broad and torsion-proof profile. The consequence of this is that, e.g., distortions occurring during pressing may lead to problems at the time of the installation in the door.
A side impact protection member comprising an extruded hollow section made of aluminum (DE Patent No. 37 09 489) has been known as well. In this design the hollow section has projecting material strips in the area of its comers, and the said material strips are provided with recesses in the area of the longitudinal center of the side impact protection member in order to prevent the hollow section from breaking and to guarantee a uniform deformation of the side impact protection member.